Report: WDL Formosan Subterranean Termite Resistance to Polyguard Samples and Southern Pine Wood Control

Transcription

1 Formosan Subterranean Termite Resistance to Polyguard Samples and Southern Pine Wood Control Report #: WDL John Muncaster Polyguard Submitted By: Wood Durability Lab Louisiana Forest Products Development Center School of Renewable Natural Resources LSU Agricultural Center Baton Rouge, LA Tel. (225) Fax (225) December 11, 2015 We kindly request that all public references to the contents of this report be attributed to LSU AgCenter s Wood Durability Lab Page 1 of 12

2 TABLE OF CONTENTS BACKGROUND OBJECTIVES MATERIALS AND METHODS RESULTS CONCLUSIONS REFERENCES CITED RESULT TABLES FIGURES 7 END OF REPORT Page 2 of 12

3 Background The Wood Durability Laboratory (WDL) at the LSU Ag Center became an ISO accredited laboratory through the International Accreditation Services (IAS) accreditation system on March 1, Additional test standards were added by IAS to the WDL approved scope of services on July 24, 2008, November 20, 2009, May 31, 2012, and January 24, 2014(Table 1). The lab essentially has been operating under ISO Guidelines for over six years. This report is compliant with ICC-ES AC85. This report has not been reviewed by a licensed professional engineer. Samples and information sheets on traceability of samples were provided by the sponsor. The results from this test only relate to the items tested. Table 1. Current WDL test methods accredited by IAS. Fields of Testing Accredited Test Methods ASTM Standards D 143 2, D , D (Methods A and D only) and D (Test methods referenced in Annex A3 and A4 Wood testing only); Test methods referenced in Section 4.0 of ICC-ES Acceptance Criteria AC257 3 ; APA PS-1 5 (Section 6.1 Bond Durability) ASTM Standards D , D , D , D , D3345 1, Wood D and D ; AWPA Standards A9 4, E1 1, E5 3, E7 1, E9 3, preservatives E10 1, E11 1, E12 1, E16 3, E18 3, E21 4, E22 2, E23 2, E24 1, E26 4 and E29 5 ; WDMA Standards TM-1 1 and TM Approved March 1, 2008, 2 Approved July 24, 2008, 3 Approved November 20, 2009, 4 Approved May 31, 2012, and 5 Approved January 24, OBJECTIVES The objective of this study was to evaluate Polyguard samples for resistance to subterranean termites using the choice test method. The test included Polyguard samples, untreated pine controls, and untreated pine controls. Formosan subterranean termites were used for this choice test. MATERIALS AND METHODS Termite Testing The test was performed in accordance with American Wood Protection Association (AWPA) E1-15 Standard Method for Laboratory Evaluation to Determine Resistance to Subterranean Termites (AWPA 2015). The choice method was used. These tests were started on 11/3/15 and concluded on 12/1/15. The Polyguard samples consisted of pine control samples that were sandwiched in a rubber sealant with the edges having sealant only, see figure #1. Page 3 of 12

4 Originally this test was setup as a no-choice test, where the termites are not given a choice of an experimental product vs. an untreated sample. The Polyguard samples were placed in a jar alone. This test resulted in the termites making their way through only one, sample #2, of the Polyguard sealant samples. After the test the samples were cleaned and put in a drying oven. Inadvertently they were left in the oven for too long and the sealant melted. Although termites seemingly ate through the sealant, there was no attack on the untreated wood, see figures #2 through #5. After this test, it was decided to run this test as a choice test. The choice test consisted of 5 Polyguard samples and 5 pine choice controls in the same jar and 5 pine control samples. The Polyguard samples were provided to the WDL. Polyguard testing samples measured 1.5 in. x 1.5 in. x 0.5in. The southern pine controls and choice controls measured 1in. x 1in. x ¼ in. All pine control samples were milled in the correct grain orientation and contained 4 to 6 rings per inch. Table 2. Sample identification and labeling. Polyguard Choice Test: WDL Charge ID Sample ID MC Sample ID Control 1-5 6mc-7mc Choice Control 6-10 choice Polyguard 6-10 N/A Each testing jar contained 150 g of autoclaved sand and 30 ml of distilled water. A sample was placed in each jar on top of the sand on an aluminum barrier to prevent chemical leaching. The jar containing the Polyguard samples also contained an untreated pine choice control. Formosan termites were obtained from Brechtel State Park (Algiers, La) on 11/3/15 and added to the E1-15 test on 12/1/15. Four hundred termites, determined by weight, were introduced to each jar on the side opposite to the sample. Samples of termites were taken, weighed and an average weight per termite determined. An average of g per termite was determined for the Formosan termites. Therefore, each jar contained 1.854g of Formosan termites respectively, see figure #11. After 28 days of exposure, the samples were removed and cleaned with distilled water to remove termites and sand, rated and oven dried. Each sample was rated based on the following AWPA rating system: 10 Sound 9.5 Trace, surface nibbles permitted 9 Slight attack, up to 3% of cross sectional area affected 8 Moderate attack, 3-10% of cross sectional area affected 7 Moderate/severe attack, penetration, 10-30% of cross sectional area affected 6 Severe attack, 30-50% of cross sectional area affected 4 Very severe attack, 50-75% of cross sectional area affected 0 Failure Page 4 of 12

5 The data obtained were analyzed for resistance with means and standard deviations determined (SPSS 2015). The Least Significant Difference (LSD) mean separation test procedure was used (Steel and Torrie 1980). Different capital letters within columns indicate that significant differences were found at the significance level α= Significant differences were not found among treatments when means shared the same letters within columns. All data and records collected during the tests are maintained at the WDL and are available upon request. RESULTS Table 3 provides a summary of the means (Ave.) for the primary data of interest (i.e., percent mortality, percent weight loss, and treatment ratings). Table 4 provides information on statistical differences determined between treatments for the experimental variables using the LSD test procedure. Figures 6-10 show the choice samples after 28 days of testing. Percent Termite Mortality. All live termites were counted after the 28-day exposure period. Percent mortality was obtained with this calculation: ((initial termites live termites) / initial termites)*100. As shown in Table 4, mean percent mortality for the untreated southern pine wood control jars was 10.15%. Mean percent mortality for the Polyguard/choice jars was 18.15%. The mean mortality values from control and Polyguard/choice jars are significantly different from one another. Percent Sample Weight Loss. Percent weight loss was based on the original oven dry weight using this formula: (calculated ODWt final ODWt)/calculated ODWt. The test samples oven dry weight was determined by measuring the moisture content of the matched sample and using it to calculate the sample oven dry weight. The final oven dry weight was determined by oven drying the sample after the test. As shown in Table 4, the mean percent weight loss for the untreated southern pine controls was 36.25%, which is indicative of acceptable termite vigor. The mean percent weight loss for the choice controls samples was 21.83%. Weight loss for the Polyguard samples was not determined. The mean weight loss values from the controls and the choice control samples are significantly different from one another. Sample Rating. The rating of each sample was done visually by estimating the extent of damage. The rating scale used was 0 to 10 with 0 being complete failure and 10 being sound as outlined in AWPA E1-15. Each of the 5 untreated controls received a visual rating of 0, indicating failure. The choice controls received a visual rating of 4, indicating very severe attack, 50-75% of cross sectional area affected. The Polyguard samples received visual ratings of 9.5, indicating trace, surface nibbles. The mean sample rating values from control, choice control, and Polyguard samples are all significantly different. CONCLUSIONS This testing successfully demonstrated that the Polyguard samples provided excellent protection from Formosan termite attack. This choice test indicates that, if given the Page 5 of 12

6 choice, termites will feed on untreated pine wood instead of the rubber coated Polyguard samples. The untreated southern pine control yielded results for mortality, sample weight loss, and visual ratings that were consistent with previous test results and indicative of strong termite vigor and performance, and hence the test data are considered to be valid. REFERENCES CITED American Wood Protection Association (AWPA) Standard method for laboratory evaluation to determine resistance to subterranean termites (E1-15) book of standards. Birmingham, AL. SPSS for Windows Chicago, IL. Steel, R.G.D. and J.H. Torrie Principle and procedures of statistics A biometrical approach. 2 nd edition. McGraw Hill. New York. 633 p. Table 3. Summary data for termite mortality, sample weight loss, and sample rating. Sample ID Mortality (%) % Mean (stdev) Wt. Loss (%) % Mean (stdev) Rate (0-10) (2.38) (3.99) ch ch ch ch (1.62) (2.60) 4 10 ch * N/A 9.5 7* N/A 9.5 8* N/A N/A 9.5 9* (1.62) N/A (N/A) * N/A 9.5 *These are the Polyguard rubber coated samples. % Mean (stdev) 0.0 (0.0) 4.0 (0.0) 9.5 (0.0) Table 4. Summary data for termite mortality, sample weight loss, and sample rating with corresponding LSD grouping. Sample Mortality (%) LSD Weight Loss (%) LSD Rating (0-10) LSD Control A A 0.0 A Choice B B 4.0 B Polyguard B N/A N/A 9.5 C * Groups containing the same capital letter indicate that significant differences were not found at the 95% confidence interval. Page 6 of 12

7 Figure #1, untreated samples sandwiched with Polyguard sealant. Page 7 of 12

8 Figure #2 Figure #3 Figure #4 Page 8 of 12

9 Figure #5 Figures 2 5: attack on sample #2 when tested in the no-choice test. No attack on the untreated wood sample surrounded by Polyguard sealant. Page 9 of 12

10 Figure #6 Figure #7 Figure #8 Page 10 of 12

11 Figure #9 Figure #10 Figures 6 10: Samples after 28 days of exposure using the no-choice test method. There was no attack on the Polyguard sealant, but the untreated choice samples were heavily attacked. Page 11 of 12

12 Figure #11: Samples after 28 days of testing using the choice method. END OF REPORT Page 12 of 12